We use the description Magnetized thru thicknessto identify the locations of the poles on our block magnets. The thickness is always the last dimension listed for block magnets. If you take one of our block magnets and place it on a flat surface with the thickness dimension as the vertical dimension, the poles will be on the top and bottom of the magnet as it sits.For example: On one of our blocks of 1x 1/2x 1/8thick (25.4 x 12.7 x 3.17mm). If you place one of the blocks so it is on a flat surface with 1/8(3.17mm) as the vertical dimension, the poles will be on the top and bottom as the magnet sits. This means the poles are located in the middle of the 1x 1/2sides (25.4 x 12.7mm).